Catalytic degradation of chlorpheniramine over GO-Fe3O4 in the presence of H2O2 in water: The synergistic effect of adsorption.

Chlorpheniramine is a pharmaceutical widely used and found in water environments. Besides hormone disruption and adverse environmental effects, chlorpheniramine forms carcinogenic nitrosamines during disinfection. We have demonstrated previously the efficient adsorption of chlorpheniramine from aqueous solution onto graphene oxide-magnetite composite (GO-Fe3O4). The present study focused on the elimination of chlorpheniramine and the formation of nitrosamine byproducts during reaction with H2O2 over GO-Fe3O4 catalyst. The effects of the morphology of GO-Fe3O4 in terms of iron fraction, pH, concentrations of H2O2 and organic matters on chlorpheniramine removal in the GO-Fe3O4-H2O2 system were investigated. Chlorpheniramine was efficiently removed at pH 9 when GO-Fe3O4 had a higher micropore volume and surface area. Kinetics study showed that both oxidation (k = 5.1(±0.2) × 10-3 (mg g-1)-1 min-1) and adsorption reactions (k = 2.7(±0.1) × 10-3 (mg g-1)-1 min-1) fitted well with the second-order kinetics model. The adsorption sites on the GO-Fe3O4 surface could be different from those involved during catalytic oxidation. Chlorpheniramine removal decreased by 44.9% in the 5th cycle without regeneration due to the structural fracture of GO-Fe3O4. A tentative pathway of chlorpheniramine degradation and nitrosamine formation by GO-Fe3O4-H2O2 was proposed. GO-Fe3O4 was an adsorbent and effective catalyst in chlorpheniramine degradation by H2O2 that exhibited limited nitrosamine formation at moderate reaction time.